Mechanical fuel pump



p 1959 E. A. JOHNSON 2,905,097

MECHANICAL FUEL. PUMP Filed June 30, 1958 A INVENTOR.

5 ELDON A. JOHNSON ATTORNEY e9 "IIIAMIIZ 2,905,095" MECHANICAL FUEL PUMP Eldon A. Johnson, St. Louis, Mo, assignor to ACF Industries, Incorporated, New York, N .Y., a corporation of New Jersey Application June so, was, Striai No. 745,350 14 Claims. or. 103 150 The invention relates to pumps, and more particularly to a diaphragm pump of a type especially suitable for pumping fuel to the carburetor for an internal combustion engine, the diaphragm of the. pump being operable by a drive from the engine.

A diaphragm pump of the class described conventionally comprises means defining a pumping chamber, a diaphragm closing the pumping chamber and adapted for movement in one direction through a discharge stroke and back in the opposite direction through an intake or suction stroke, and means for driving the diaphragm. The driving means conventionally comprises a spring for driving the diaphragm through a discharge stroke, and an engine-driven cam means for driving the diaphragm back through a suction stroke. The action of this type of pump is such that there is apt to be a thump on the suction stroke of the diaphragm, and the thumping needs to be muffled. A pump of this class usually has a housing enclosing the diaphragm and the spring. This housing is adapted to act as a muflie, and the principal object of this invention is to provide a construction for so utilizing the housing without substantially impeding the action of the pump; In general, this object is attained by providing the housing with check valve means which acts upon a suction stroke of the diaphragm toallow only restricted venting of air fromthe housing, but which acts on a discharge stroke of the diaphragm to allow relatively unrestricted admission of air to the housing. With this arrangement, the thumping on suction strokes may be effectively muflied so that it is substantially inaudible from outside the housing, without building up such air pressure in the housing on a suction stroke of the diaphragm as would adversely affect the suction stroke, and without developing such vacuum in the housing on adischarge stroke of the diaphragm as would adversely impede the discharge stroke. Other objects and features will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the constructions hereinafter described, the scope of the invention being indicated in the following claims.

In the accompanying drawings, in which several of various possible embodiments of the invention are illustrated,

Fig. 1 is a vertical section of a pump constructed in accordance with this invention as it appears when in stalled with an engine, parts being shown in their position adjacent the end of a discharge stroke;

Figs. 2 and 3 are sections taken on lines 2-2 and 33, respectively, of Fig. 1;

Fig. 4 is a view of a check valve member as it appears from line 44 shown in Figs. 2 and 3;

Fig. 5 is an enlarged fragment of Fig. 1 showing one way in' which the check valve member may be installed;

Fig. 6 is a view similar to Fig. 5 showing another way in which the check valve member may be installed;

Fig. 7' is a section" illustrating a modification; and,

2, 95,997 Patented Sept. 22, 1959 Fig. dis a section taken on line 88 of Fig. 7.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Referring to the drawings, a pump of this invention is shown generally to comprise a bowl 1, a cup-shaped body 3 which serves the dual purpose of closing the bowl 1- and providing a pumping chamber 5, a diaphragmv 7 closing: the cups-haped body 3, a coil compression spring 9- for biasing the diaphragm in discharge direction, and a cast casing 11.. The space-within the bowl 1 is divided by an annular partition 13 constituted by a tubular projection extending from body 3 into a central intake chamber 15* and a surrounding discharge chamber 17. The base 119 ofi bowl 1 has. a central inlet port 21 in which is secured: an inlet nipple 23. The bowl has a discharge port 27 in which is fixed a discharge nipple 29. Body 3 is forme'd with a circular series ofsl'ots such as indicated at- 33 constituting intake valve ports providing for communication from intake. chamber 15 to the pumping chamber 5 under controli' of an intake check valve 35. The body is also formed with a circular series of slots such as i'ndicat'edi at 37 surrounding slots3'3 and constituting discharge: valve ports providing for communication from pumping; chamber 5' to discharge chamber 17 under control of a discharge check valve 39.

The casing 1'1 comprises a conical portion 40 constituting a housing for'the: diaphragm: 7 and spring 9, and a flaringa portion 431i extending laterally from the small end of spring. housing 4%: constituting a housing for a rocker arrn 43.. Thediaphra'gm 7 isifixed on the lower end of a stem. 45 which extends slidably through a packing member 47 held in theupper endof housing 40; Spring 9 surroundslstemfiig.reacting from a gland 48 bearing against packing member 47'. Stem 45 extends up into the inner end of rocker arm housing 41 through an opening 49. A pivot" pin. for the rockerarm is indicated at 52. The rockerarmhas a slot 55 extending outward from its inner end: receiving the stem 45. The latter has a head 57 at its upperrend engageable'by the rocker arm.

A leaf. spring. 59 has one end secured as by a rivet 60 to-the rocker arm 43 and extends towards the outer end of. the rocker arm. Its free-end is normally spaced from theouter endportionof arm 43. When the pump is installed: on an engine, the free end portion oftlie spring 59 isen'ga'ge'd' by an engine driven cam 61. The action of the cam is. such that during a part of its cycle, the rocker arm" 43 is free to rock counterclockwise from a retractedposition (not shown) to the advanced position inwhich it is shown in Fig. 1. With the rocker arm freed'fbr such" movement, the stem 45 is freed to enable spring 9'to' drive the diaphragm 7 down through a discharge stroke if fuel is free to flow out of pumping chamber 5and discharge chamber 17 (as determined by the requirements of a carburetor supplied by the pump). Whenrtherocker arm rocks counterclockwise from its retraeteda position, leaf spring 59' remains in engagement with the cam-6i flexingin the direction toward the rocker ar-m.- During another part of the cycle, the cam- 61 is adapted to act through the leaf spring 59 to drive the rocker arm back tothestated retracted position, thereby pulling. up the. stem 45 and driving the diaphragm up through a suction stroke. Upon a suction stroke, the diaphragm thumps. Further details of the pump construction may be ascertained, if needed,,from the application of Eldon A. Johnson and Donald R. Compton, Serial No. 739,241, filed June 2., 1958 (case 973).

In accordance with this invention, check valve means indicated at 63 is provided acting on a. suction stroke. (upstroke) of the diaphragm 7 to allow only restricted venting of air from housing40-' and acting on a discharge stroke (downstroke) of the diaphragm to allow relatively unrestricted admission of air to the housing 40. As illustrated in Figs. 1-4, this check valve means comprises a check valve member 65 constituted by a sheet metal leaf spring or reed, held in position on the inside of the conical wall of housing 40 by a tubular rivet 67 and normally closing a, relatively large port 69 in the wall. Rivet 67 extends through a relatively small hole 71 in the wall above the port 69. The hole 73 through the rivet constitutes a restricted orifice for restricted or throttled venting of air from the housing 40 on a suction stroke (upstroke) of the diaphragm. The reed 65 extends down from the rivet past the port 69. It may be of tapering form as shown in Fig. 4, with its side edges converging from its fixed end to its free end. The reed is mounted in such manner that it is prestressed so as to be inherently biased toward closed position engaging the inside of the wall of housing 40 around the port 69. The inside of the wall of housing 40 may be made flat as indicated at 75 in the region of the reed (see Figs. 2 and 3) for flatwise engagement of the reed with the inside of the Wall. The wall may also be provided on the interior thereof with lugs 77 (see Fig. 3) on opposite sides of the reed at its fixed end for purposes of locating the reed and holding it against swinging.

One mode of prestressing the reed, as shown in Fig. 5, is intially to form it with a bend as indicated at 79 in the region of the hole 81 in the reed which receives the rivet, then flattening it out by means of the rivet when the latter is set.

Another possible mode of prestressing the reed is to form housing 40 in such manner that its interior surface is made concave as indicated at 83 in Fig. 6 between hole 71 and port 69, and to use an initially flat reed. Then when the rivet is set, the reed is constrained to follow the concave surface 83 for prestressing.

In operation of the above-described pump, upon a suction stroke (upstroke) of diaphragm 7, the reed 65 is pressed firmly against the flat surface 75 to close the port 69, and air escapes from Within the housing 40 through the restricted hole or orifice 73 in the rivet 67. This hole or orifice is so small that the thump which occurs on the suction stroke is eifectively confined Within the housing 40 for muffling purposes. While the hole or orifice 73, in being sufiiciently small for this purpose, may not vent the housing 40 so rapidly as to avoid some build-up of air pressure in the housing 40, this pressure is not such as to be disadvantageous, and actually may have an advantage in that it may reduce the tendency toward vapor lock.

On the discharge stroke (downstroke) of the diaphragm 7, the reed 65 is bent away from the surface 75 to open up the port 69 and allow relatively unrestricted admission of air to the housing 40. This avoids development of vacuum in the housing 40 such as would impede the downstroke of the diaphragm.

In the event that fluttering of the reed may cause detectable noise at idle speeds, the construction may be made such that the admission of air to the housing on discharge strokes of the diaphragm is taken care of by the orifice 73 without actuation of the reed 65. At higher speeds, noise due to fluttering of the reed is not noticeable.

Under some circumstances, the venting of the housing 40 on suction strokes of the diaphragm may be taken care of without the use of a vent such as the orifice 73 by having the reed seat so lightly that air may escape through port 69. Or, as shown in Figs. 7 and 8, the construction may be such as to allow for venting through port 69 via a groove 85 in the interior surface of housing 40 extending from port 69 beyond the reed to provide for escape of air through the groove and port 69 on suction strokes of the diaphragm. In this case, the reed may be fastened to the wall of the housing as by casting a stud 8.7 on the wall entrant in the hole 81 in the reed, and heading over the stud to hold the reed in place.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a lim iting Sense.

I claim: .33;;

1. In a diaphragm pump comprising means defining a pump-ing chamber and a diaphragm closing the chamber, a housing enclosing the diaphragm, the diaphragm being movable away from the housing through a discharge stroke and back through a suction stroke, said housing having an air inlet check valve and an air vent orifice acting on a suction stroke of the diaphragm to allow only restricted venting of air from the housing through said orifice and acting on a discharge stroke of the diaphragm to allow relatively unrestricted admission of air to the housing through said inlet check valve.

2. In a diaphragm pump comprising means defining a pumping chamber and a diaphragm closing the chamber,

a housing enclosing the diaphragm and provided with a port, the diaphragm being movable away from the housing through a discharge stroke and back through a suction stroke, said housing having an air inlet check valve and an air vent orifice acting on a suction stroke of the diaphragm to allow only restricted venting of air from the housing through said orifice and acting on a discharge stroke of the diaphragm to allow relatively unrestricted admission of air to the housing through said inlet check valve, said check valve comprising a check valve member mounted on the inside of the housing in association with said port in the housing, said member normally engaging the housing around the port, and being movable inwardly to open the port for said relatively unrestricted admission of air to the housing on a discharge stroke of the diaphragm.

3. In a diaphragm pump comprising means defining a pumping chamber and a diaphragm closing the chamber, a housing enclosing the diaphragm and provided with a port, the diaphragm being movable away from the housing through a discharge stroke and back through a suction stroke, said housing having an air inlet check valve and an air vent orifice acting on a suction stroke of the diaphragm to allow only restricted venting of air from the housing through said orifice and acting on a discharge stroke of the diaphragm to allow relatively unrestricted admission of air to the housing through said inlet check valve, said check valve comprising a resilient reed fastened at one end to the inside of the housing and having its other end free and extending over said port in the housing, said reed normally engaging the housing around the port, and being movable inwardly to open the port for said relatively unrestricted admission of air to the housing on a discharge stroke of the diaphragm.

4-. In a diaphragm pump as Set forth in claim 3, said reed being of decreasing width from its said one end to the other.

5. In a diaphragm pump as set forth in claim 3, said housing having a fiat interior surface engageable by the reed, said reed, when unstressed, being bent and fastened to the housing in flattened-out form so that it is stressed to lie flat against said fiat surface.

6. In a diaphragm pump as set forth in claim 3, said housing having a concave interior surface engageable by the reed, said reed, when unstressed, being fiat, and being fastened to the housing so that it is stressed to be curved to lie against said concave surface.

7. In a diaphragm pump comprising means defining a pumping chamber and a diaphragm closing the chamher, a housing enclosing the diaphragm and having a port, the diaphragm being movable away from the housing through a discharge stroke and back through a suction stroke, and check valve means acting on a suction stroke of the diaphragm to allow only restricted venting of air from the housing and acting on a discharge stroke of the diaphragm to allow relatively unrestricted admission of air to the housing, said check valve means comprising a reed, a tubular fastener extending through the wall of the housing and said reed whereby said reed normally engages the Wall of the housing to close the port and is movable inwardly to open the port for said relatively unrestricted admission of air to the housing on a discharge stroke of the diaphragm, said tubular fastener providing a restricted opening for said restricted venting of air.

8. In a diaphragm pump as set forth in claim 7, said reed being of decreasing Width from its said one end to the other.

9. In a diaphragm pump as set forth in claim 7, said housing having a flat interior surface engageable by the reed, said reed, when unstressed, being bent and fastened to the housing in flattened-out form so that it is stressed to lie flat against said flat surface.

10. In a diaphragm pump as set forth in claim 7, said housing having a concave interior surface engageable by the reed, said reed, when unstressed, being flat, and being fastened to the housing so that it is stressed to be curved to lie against said concave surface.

11. In a diaphragm pump as set forth in claim 7, said housing having lugs extending on opposite sides of the reed holding it against swinging on said fastener.

12. In a diaphragm pump comprising means defining a pumping chamber and a diaphragm closing the chamber, a housing enclosing the diaphragm and provided with a port, the diaphragm being movable away from the housing through a discharge stroke and back through a suction stroke, and check valve means acting on a suction stroke of the diaphragm to allow only restricted venting of air from the housing and acting on a discharge stroke of the diaphragm to allow relatively unrestricted admission of air to the housing, said check valve means comprising a reed fastened at one end to the inside of the housing and having its other end free and extending over said port in the housing, said reed normally engaging the housing around the port with the engagement such as to allow for said restricted venting through said port on a suction stroke of the diaphragm, and being movable inwardly to open the port for said relatively unrestricted admission of air to the housing on a discharge stroke of the diaphragm.

13. In a diaphragm pump as set forth in claim 12, said reed is of decreasing width from its said one end to the other.

14. In a diaphragm pump as set forth in claim 12, said housing having a groove in the interior thereof extending laterally from said port providing for said restricted venting.

References Cited in the file of this patent UNITED STATES PATENTS 

